Basic

sample.packages.flutter.lib.src.widgets.basic.3196.

This examples shows how AspectRatio sets width when its parent's width constraint is infinite. Since its parent's allowed height is a fixed value, the actual width is determined via the given AspectRatio.

Since the height is fixed at 100.0 in this example and the aspect ratio is set to 16 / 9, the width should then be 100.0 / 9 * 16.

  
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const MyStatelessWidget(),
      ),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Colors.blue,
      alignment: Alignment.center,
      width: double.infinity,
      height: 100.0,
      child: AspectRatio(
        aspectRatio: 16 / 9,
        child: Container(
          color: Colors.green,
        ),
      ),
    );
  }
}